1. Field of the Invention
The present invention relates to a method for carrying out a real time backup communication of Internet Protocol (will be referred to as xe2x80x9cIPxe2x80x9d hereinafter) communication. More particularly, the present invention relates to a method for carrying out a real time backup communication of IP communication using a public network.
2. Description of the Related Art
In recent years, a real time communication begins to be used for data such as voice and animation on Internet, Intranet and Extranet (hereafter, they are referred to as xe2x80x9cInternet networkxe2x80x9d or xe2x80x9cIP networkxe2x80x9d). Activities of IETF standardization have become active with regard to the QoS (Quality Security) control for securing the quality of the real time communication as much as possible. The main items among them are as follows:
(1) RSVP (ReSource reservation Protocol): resource reservation protocol
(2) RTP (Real-time Transport Protocol)/RTCP (Real-time Transport Control Protocol): real-time communication control protocol
(3) DiffServe (Differentiated Service): priority control using IP header
(4) RTSP (Real-time Transport Streaming Protocol): stream data Control Protocol
Only those QoS controls can not carry out the real time communication that is stable on the Internet network. For example, a real time communication call such as voice data, animation data and the like, from a transmission side node causes an error at a reception side node because of troubles of a network and a node connected to the Internet network. A real time communication that is a communication manner in a UDP (User Datagram Protocol) procedure that does not carry out a re-transmission control does not have means for detecting the trouble of the Internet network on the node side. Thus, it is impossible to judge whether the trouble results from an opposite node trouble or a network trouble.
Under such situation, a maintenance technician having a high ability who firstly detects the network trouble based on a communication error report from a user uses a method for transmitting an echo request message between nodes, and firstly checking the error based on an absence of a reply with regard to an echo answer message, and manually switching to a public network such as INS and the like, to thereby carry out a backup switching operation. The specification of the trouble reason necessary for the execution of this method requires the high maintenance technique of the maintenance technician. Moreover, the maintenance technician having such high technique needs to carry out a large number of processes to specify the network trouble and the communication trouble. Moreover, it takes a long time to carry out a series of trouble analyses from the user request to the manual operations by the maintenance technician having the high maintenance technique, which results in the large drop of related services.
Especially, associated with the down-sizing and flatting (horizontalizing) of the network resulting from the IP network in recent years, it is economically difficult to station the maintainers having the special and high techniques for respective small many networks existing in an enterprise. So, a system begins to be required in which even a maintainer holding another low typical service, namely, an amateurish maintainer assigned in each department can quickly specify the trouble reasons. In other words, the desire to establish a mechanism for economically insuring a reliability of the IP network has become popular in which the drop of the communication quality caused by the network trouble and the network delay time in the Internet network that is very economic although it is low in reliability and quality can be monitored on a user equipment side by using a cheap method, and it is possible to carry out a stable continuous communication of a real time communication call.
A related technique is disclosed in Japanese Laid Open Patent Application (JP-A-Heisei, 10-224408) as xe2x80x9cCOMMUNICATION SYSTEMxe2x80x9d. First and second communication apparatuses in this communication system have switching means, data format converting means and switching control means. The switching means contains a plurality of communication lines including a call path highway provided with a plurality of channels, which are connected to public networks, dedicated lines and inner terminals. The data format converting means connects a computer network and the call path highway, and converts a format of a transmission data between the computer network and the call path highway, and also transmits and receives a data to and from a destination communication apparatus through the computer network. The switching control means transmits and receives a call control information to and from the destination communication apparatus through the computer network, and also controls the switching means and the data format converting means so as to establish the connection using the computer network, in accordance with the data kinds at a terminal on a transmission side and a terminal on a reception destination. According to this communication system, a mutual communication can be done between the terminals, in which the data kinds are different from each other, by using the computer network without a manual operation.
Japanese Laid Open Patent Application (JP-A-Heisei, 10-65737) discloses xe2x80x9cSUBSTITUTE SERVER APPARATUS AND SERVER APPARATUSxe2x80x9d. The substitute server apparatus contains: means for carrying out a PPP connection through a public network between a network and the server apparatus, by dynamically assigning an IP address in accordance with a specified server apparatus name and a telephone number in a corresponding public network, between the network and the server apparatus; and means for accessing the server apparatus by using the dynamically assigned IP address. Accordingly, with regard to the server apparatus to be connected to the network managed by the IP address through the public network, even if it is not connected to the network at a time of the communication request and further the IP address is not determined, it is possible to connect the server apparatus to the network and dynamically assign the IP address and further communicate with the dynamically assigned IP address based on the server apparatus name.
Moreover, Japanese Laid Open Patent Application (JP-A-Heisei, 9-130429) discloses xe2x80x9cCOMMUNICATION SYSTEMxe2x80x9d. In this communication system, a line/packet converter is connected between a computer network and a call path highway in a private switch. A computer terminal transmits and receives a call control packet to and from the private switch through the computer network. The line/packet converter converts a format of a transmission data between the computer network and the call path highway. Accordingly, it is possible to connect the computer network, a subscriber line, and an extension line so that the computer terminal can communicate with another communication terminal through a public network and an extension line network.
Therefore, an object of the present invention is to provide a method for carrying out a real time backup communication of IP communication, which can protect a drop of a communication quality caused by a network delay time and a network trouble in an Internet network that is very economic, by using a cheap and simple method.
Another object of the present invention is to provide a method for carrying out a real time backup communication of IP communication, which can attain a technique for economically insuring a reliability of an Internet network by executing a real time communication stably and continuously.
Means for solving the above-mentioned problems are explained as follows. A number, a symbol or the like together with parentheses xe2x80x9c( )xe2x80x9d is given to a technical item appearing in the explanation. The number, the symbol or the like coincides with a reference number, a reference symbol or the like given to a technical item constituting at least one embodiment or an example among a plurality of embodiments or a plurality of examples in the present invention, especially a technical item illustrated in a drawing corresponding to the embodiment or the example. Such reference numbers and reference symbols evidently denote a corresponding relation between the technical item noted in the claims and the technical item in the embodiment or the example. Such corresponding relation does not imply the interpretation that the technical item noted in the claims is not limited to the technical item in the embodiment or the example.
A method for carrying out a real time backup communication of IP communication according to the present invention comprises a step of detecting an occurrence of a trouble in a real time communication on an IP network (100) connecting between a transmission side node (120) and a reception side node (130), and a step of automatically bypassing a communication call of the real time communication performed between the transmission side node (120) and the reception side node (130), from the IP network to a public network (110), based on the detection. Such a bypass operation enables the continuation of the real time communication. The occurrence implies a generation of a delay time to the extent that the quality of the real time communication can not be secured. ICMP is used for the periodical transmission and reception.
There may be a case that a real time communication call is newly generated during the course of the real time communication. In this case, the bypass operation of the new real time communication call to the public network (110) is performed to thereby enable the real time communication. If the trouble is recovered, the real time communication is returned from the public network back to the IP network.
There may be a case that the trouble is induced even in the public network. During the bypass operation, the occurrence of the trouble is detected in the real time communication on the public network connecting between the transmission side node and the reception side node. The detection is executed by detecting a time in the periodical transmission and reception with regard to an echo request message and an echo answer message between the transmission side node (120) and the reception side node (130). In the detection during the bypass operation, if the echo request message is normally received while the trouble is induced on the public network (110), it is judged that the public network (110) is normal and the node (120 or 130) is abnormal.
The detection on the IP network (100) is executed by detecting the time of the periodical transmission and reception with regard to the echo request message and the echo answer message between the transmission side node (120) and the reception side node (130). In the detection, if the echo answer message is normally replied, it is judged that the IP network (100) has no trouble and the node (120 or 130) has a trouble. Typically, the discrimination between the trouble in the node (120, 130) and the trouble on the IP network (100) can be done by detecting the recovery of the trouble on the IP network (100) and detecting the occurrence of the trouble in the real time communication on the public network (110).